A typical motor vehicle, such as a car, may have an internal combustion engine at a distance from a drive axle. A propeller shaft transmits torque from the engine to the axle, usually via a multi-speed transmission. In the most common arrangement the transmission is in unit with the engine, but the transmission may alternatively be in unit with the drive axle.
A propeller shaft is typically 1-2.5 m long, and may include one or more support bearings towards the centre thereof. Where a vehicle has several drive axles, a propeller shaft may be provided for each of them.
A propeller shaft should be rotationally balanced if intended to turn at speed, as is the case in a vehicle. Typically in a vehicle, a propeller shaft must be designed for rotation at engine speed without exhibiting significant out of balance forces. Imbalance may be noticeable to the vehicle driver and vehicle occupants, and may induce noise and vibration in the vehicle structure and driveline in addition to reducing the life of bearings associated therewith.
Although a propeller shaft may have satisfactory rotational balance, it is also necessary to ensure that the end couplings thereof allow co-axial connection with the input and output drive members. Run-out, as a result of non-axial connection can result in generation of significant out of balance forces.
One kind of conventional connection provides the propeller shaft with a flange mounting for connection to a corresponding flange of an input member (e.g. transmission output shaft) and/or an output member (e.g. input shaft of a drive axle). Simple flange connections provide for fixing axially and radially, but do not eliminate the possibility of run-out at the coupling, and hence imbalance.
An alternative is to use a male/female spline connection to transmit torque. This arrangement is generally of lesser radial size, and thus less susceptible of generating out of balance forces; however a means of fixing against relative axial movement is required. Additionally a small degree of radial clearance is necessary to facilitate assembly of the splined connection, so that the possibility of run-out at the coupling is not wholly eliminated.
In a refinement, a collet-type clamp arrangement may be provided to fix a splined connection axially whilst centralizing the propeller shaft with the neighbouring drive/driven member.
What is required is a positively fixed connection which has the capability to eliminate run-out whilst at the coupling ensuring ease of assembly and disassembly.